Vehicle Crime
Background to the 2001 Car Theft Index
This document is published for archival/historical purposes. It will not be updated.
This page outlines the methodology used for producing the 2001 car theft index. The methodology was designed by the Home Office Policing and Reducing Crime Unit, who contracted the data processing to the Transport Research Laboratory.
Data sources
The car theft index is based on thefts of cars and excludes attempted thefts and thefts from cars.
The index is based on cars reported stolen in England, Scotland and Wales which are recorded on the Police National Computer (PNC). The PNC only contains details of unrecovered vehicles because once a stolen vehicle is recovered it is deleted from the system. The data used in the theft index were obtained from Experian Ltd who receive PNC stolen vehicle data but do not delete records when vehicles are recovered. An additional weighting factor was also built into the theft figures to account for those recovered vehicles which were not picked up by the data-set provided by Experian.
The time-frame for the stolen vehicle information was 1st January 2000 to 31st December 2000.
The vehicle parc (population of vehicles on the road) data were collected by the Driver and Vehicle Licensing Agency (DVLA) and obtained through the Society for Motor Manufacturers and Traders (SMMT). This consisted of all vehicles licensed with DVLA on 31st December 2000.
Calculating the index
The theft rate for particular makes and models was calculated using the following formula:
Number of vehicles reported stolen
------------------------------------------- X 1000 = Theft rate
Number of vehicles licensed with DVLA
Using this formula, a theft rate was calculated for each model of car by each year of registration between 1986 and 2000.
In order to produce a more readable document, the years of registration were grouped into bands of three years from 1986 onwards, creating six age bands (Pre-1986, 1986-1988, 1989-1991 etc.). It should be noted that the year of registration is the year of first registration where this information is available. However, in a few cases vehicles have been re-registered and this results in some vehicles which have not been produced for a number of years having a recent date of registration.
Individual theft rates were grouped into three broad bands indicating those which were ‘most at risk’, ‘medium risk’ and ‘lower risk’. These bands were produced by taking the 20th and 80th percentile in the rates of theft. This means that 20% of cars will be classified as ‘lower risk’, 60% as ‘medium risk’ and 20% as ‘most at risk’.
Using the 20th and 80th percentiles to distinguish between bands produced the following cut off points in the theft rates for both the 1998 and 1999 indices:
Higher risk = more than 20 cars stolen in every 1000 on the road.
Medium risk = between 4 and 20 cars stolen in every 1000 on the road.
Lower risk = up to 3 cars stolen in every 1000 on the road.
About the spreadsheets
The attached spreadsheets contain the data underlying the 2001 car theft index.
These spreadsheets are written in Microsoft Excel version 97 and can be downloaded by clicking on the links above.
Last update: Wednesday, August 27, 2008